The BAC meet yesterday at 4 PM. During the meeting the committee reviewed all of the comments that you submitted. After discussion they met with me to discuss the following four questions.
1. Question 18 Blue and 21 Pink
It appears that the confusion about this question arose over whether the answers related to only the reactions listed in each prompt or the entire process. The question is intended to relate only to what is occurring in each answer prompt. So the correct answer is e) none of the above.
Some students thought that they should interpret the question by examining whether the entire process could produce ATP. Because photosystems are involved in photosythesis then answer (a) would be correct. Because both lactic acid fermentation and alcohol fermentation are part of anaerobic respiration both answers b and c could be correct. However, there is no choice for "all of the above" which would be the correct answer if the question is interpreted this way.
Answer (e) remains the only correct answer.
2. Question 24 Blue and 29 Pink
I did not really understand the confusion related to this question. Some people apparently thought that I must be talking about CAM plants in answer (a) because CAM plants close their stomata at night (no light conditions, not low light conditions). The information in answer (a) is not accurate because plants do not close their stomata in low light conditions.
Answer (c) remains the only correct answer.
3. Question 33 Blue and 37 Pink
I found this absorption spectrum of carotene from a study on the internet. To answer this question correctly I expected you to know (1) that the photosynthetic pigments found in C3 plants like ferns were chlorophyll a and b and carotene. I expected that you would all know that chlorophyll is green and that the reason it is green is that it reflects the green wavelengths of light and absorbs the other wavelengths. Thus, green pigments have two major absorption peaks at the low end and high end of the visible light wavelengths and reflects the wavelengths in the middle.
Carotene is orange so it reflects the yellows, reds, and oranges and absorbs the rest.
In order to understand what absorption spectrums should look like you need to understand the relationship between wavelength and color (see Figure 10.6 in the book).
The confusion about this question apparently arises about whether the slight increase in absorbance that occurs around 670-680 nm is an absoprtion peak. From reading the graph you see that this pigment asborbs less than 10% of the light of this wavelength. Clearly, this little blip on the graph does indicate an absorption peak at longer wavelengths. (saying that blip is an absorption peak is equivalent to defining where the overpass of the loop passes slide road, the highest point in Lubbock, as a mountain).
It is not possible for a pigment that reflects virtually all light larger than 600 nm to appear to be green. Thus, the pigment shown in the figure must, by analysis of the absorption spectrum and by elimination be carotene.
When I met with the BAC representatives yesterday afternoon I told them that I would accept (a) Chlorophyll a as a correct answer as well. However, after giving this much too much thought over night, I have decided that chlorophyll a is not an acceptable answer for this question. Sorry to have changed my mind, but I think that this is the correct way to reward students with a strong understanding of how to interpret absporption spectrums.
Answer (c) remains the only correct answer.
4. Question 50 Blue and Question 3 Pink
Apparently, confusion with this question arose over the term "facts". I tried to make it clear that there were parts of the climate change story that were "facts" that virtually every body agreed upon and other parts of the story were conclusions drawn from different kinds of evidence.
It is a fact that the atmospheric concentration of carbon dioxide has increased over the last 50 years (see the Mauna Loa curve) and that carbon dioxide functions as a green house gas. It is also a fact that the global climate models that include the effects of human activity on atmospheric carbon dioxide concentration predict the temperature changes that have occurred over the last century than the models that excluded the effects of humans. This led the IPCC to conclude that it was "very likely" that humans have caused global climate change. This represents the best current conclusion drawn by the world's experts on this subject, but does not represent a fact.
Answer (d) remains the only correct answer.
The answers shown in the previous blog post are the correct answers for this exam.
Thanks again to the members of the BAC for investing the time and effort in attempting to make the testing process for BIOL 1404 as fair as possible.
